Throwoff mechanism for printing presses



Dec. 11, 1956 J. R. WOOD THROWOFF MECHANISM FOR PRINTING PRESS ES 7 Sheets-Sheet 1 Filed March 19, 1953 INVENTOR. .jjnra-zs W000 drrvpvsys Dec. 11, 1956 J. R. WOOD 2,773,445

THROWOFF' MECHANISM FOR PRINTING PRESSES Filed March 19, 1953 '7 Sheets-Sheet 2 fia. 2

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THROWOFF MECHANISM FOR PRINTING PRESSES Filed March 19, 1953 I 7 Sheets-Sheet 5 IN VEN TOR.

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THROWOFF MECHANISM FOR PRINTING PRESSES '7 Sheets-Sheet 6 Filed March 19, 1953 ull t INVENTOR.

122 12a 425 fi/ms's 4. W000 443 t W BY Won 2 wynms Arrways Dec. 11, 1956 J. R. WOOD THROWOFF MECHANISM FOR PRINTING PRESSES 7 Sheets-Sheet 7 Filed March 19, 1953 imizimmm uvmvroa. JPIMES ,6 W000 gm flrraezveys United States Patent THROWOFF MECHANISM FOR PRINTING PRESSES James R. Wood, De Bary, Fla., assignor to Harris-Seyhold Company, Cleveland, Ohio, a corporation of Delaware This invention relates to improvements in cylinder throwofi mechanism for printing presses, and has to do particularly with means for throwing off the intermediate cylinder in a series of three cylinders, first from one of the remaining cylinders and then from the other, and for throwing the intermediate cylinder on again in the same sequence. In the specific embodiments illustrated herein the invention is applied to a throwoff mechanism for the blanket cylinder of a rotary offset press. The present application is a continuation-in-part of my copending application Ser. No. 49,396, filed September 15, 1948, now abandoned.

In order to accomplish the purpose stated it is convenient to mount the shaft for the blanket cylinder in a pair of inner eccentrics and to mount the inner eccentrics in a pair of outer eccentrics. In previous constructions following this general plan one pair of eccentrics has been held against rotation while the other pair were turned either to throw off or throw on the blanket cylinder with respect to one of the other cylinders, and then to operate the second pair of eccentrics similarly to complete the sequential throwoff or throwon. This has presented difficulties for the reason that it is necessary, either during the throwing OH or the throwing on operation, depending upon whether the outer or the inner eccentrics are moved first, to move the outer eccentrics at a time when the blanket cylinder is being held under pressure againt one of the other cylinders. As a result of this pressure, high frictional forces are set up between the outer eccentrics and the frame of the press, and between those same eccentrics and the inner eccentrics, which frictional forces strongly oppose movement of the outer eccentrics. What may be termed a wedging action occurs, each outer eccentric as it turns acting as a wedge being forced between two stationary surfaces in a manner tending to move them apart.

One of the objects of the present invention is the provision of a construction wherein the wedging action above referred to is avoided and easy and smooth operation is accomplished.

Another object is the provision of relatively simple mechanism for operating the sequential throwoff.

Still another object is the provision of novel means responsive to the throwoif of the blanket cylinder from the first of the other two cylinders for setting in motion the throwoif movement of the blanket cylinder from the second of the other two cylinders.

Another object is the provision of means for causing the two sets of eccentrics to move together about the axis of the outer eccentrics in one of the steps of the sequential movement and for causing the inner eccentrics alone to turn within the outer eccentrics in the other step.

Other objects and features of novelty will appear as I proceed with the description of that embodiment of the invention, which for the purposes of the present application, I have illustrated in the accompaying drawings, in which ice Fig. 1 is a diagrammatic side elevational view of a printing unit of a rotary offset printing press in running condition, and illustrating the preferred form of my improved throwoff mechanism in which movement of inner and outer eccentrics together produces throwoff of the blanket cylinder from the plate cylinder followed by movement of the inner eccentrics alone for producing 'throwoff from the impression cylinder.

Fig. 2 is a similar view showing the condition of the mechanism at the time throwoff from the plate cylinder has been completed.

Fig. 3 is a similar view showing the condition of the mechanism at the time throwoif from both cylinders has been completed.

Fig. 3a is a similar view showing the condition of the mechanism at the mid-point in the sequential movement from the fully off position of the blanket cylinder back to on position, that is in this figure the blanket cylinder is in contact with the plate cylinder but not yet in contact with the impression cylinder.

Fig. 4 is a plan view of the unit.

Fig. 5 is a detail view taken substantially on the section line 5--5 of Fig. 1 but on a larger scale.

Fig. 6 is a fragmental detail view of means for manually controlling the throwofi of the blanket cylinder from the impression cylinder.

Fig. 7 is a fragmental detail View of an adjustment means for the link which is pivotally connected with the outer eccentric.

Figs. 8 and 9 are detail plan views of index plates mounted on the links connected with the outer and inner eccentrics, and

Fig. 10 is a view similar to Fig. 1 of a modified form of the invention in which movement of the inner eccentrics alone produces throwofi' from the plate cylinder,

while movement of the two sets of eccentrics together about the axis of the outer eccentrics produces throwofi from the impression cylinder, the parts being shown in this figure in the normalrunning condition of the press.

Referring first to Figs. 1 to 9 inclusive of the drawings, the plate, blanket and impression cylinders of a unit of a rotary offset printing press are shown at 10, 11 and 12 respectively. Cylinder 12 is provided with sheet grippers 13, to which sheets are delivered by a suitable feeding mechanism if the press be a single unit press or if the unit illustrated be the first one' of a multi-unit press. If the illustrated unit be a unit other than the first one of a multi-unit press, then sheets would be delivered to grippers 13 from sheet transfer means interposed between consecutive units.

The side members of the frame of the machine are indicated at 14 and 15. The shafts for the cylinders 10 and 12 are mounted in fixed bearings in these side frame members. cylinder 12. In the frame members 14 and 15 are mounted outer eccentrics 18 and 19, and within these outer eccentrics there are mounted inner eccentrics 20 and 21. Shaft 17 for blanket cylinder 11 is a dead shaft, that is, it is stationary in the ordinary operation of the machine. The inner eccentrics 20 and 21 are secured to shaft 17 by means of keys 22 and 23, so that when eccentric 20 is turned for throwofi or throwon purposes the same angular movement is imparted through shaft 17 to eccentric 21. Cylinder 11 turns on shaft 17, being driven by a gear 24 which meshes with similar gears, not shown, on the cylinders 10 and 12.

In the drawings the axis of shaft 17 is marked S, the axis of inner eccentrics 2t and 21 is marked I and the axis of the outer eccentrics 18 and 19 is marked 0. In Fig. 1 the bearing for the outer eccentric 18 is indicated by the broken line 28, the bearing for the inner eccentric 20 is indicated by the broken line 29 and the bearing A cam 16 is keyed to shaft 9 ofv of shaft 17 within the inner eccentrics is indicated by the broken line 30.

The outer eccentric 18 has an upwardly extending projection 31 which is provided with a pair of upwardly projecting ears 32. A pin 33 is oscillatably mounted in these ears. A link 34 threaded part way from its free extremity passes through a smooth hole in pin 33. Between ears 32 pin 33 is provided with flats against which sleeves 35 and 36 threaded onto the link bear. These sleeves merge with integral nuts 37 and 33 in order that the sleeves may be turned readily upon the threaded portion of the link 34. Sleeve 36 is also provided with a cylindrical portion 38' upon which a further sleeve 39 is mounted. The latter sleeve fits loosely on cylindrical portion 38' and is provided with a setscrew 39'. by which it may be clamped in desired position. Sleeve 39 has a cylindrical enlargement 40 provided with nine evenly spaced gauge grooves 41 marked in successive thousandths of an inch indicating the relative positions of cylinders 19 and 11. An index plate 42 overlies the enlargement 40, being attached to a collar 43 on link 34 by means of a screw 44. The index plate 42 is also provided with gauge marks which cooperate with. a peripheral gauge mark 45 on enlargement 40. As will be apparent, adjustments of of an. inch are readily made and gauged. by the described construction. When an adjustment is to be made, nut 37 is loosened and nut 33 is turned to a desired gauge marking and then nut 37 is turned forward until pin 33 is snugly held between the two sleeves 35 and 36.

The opposite end of link 34 is connected by a. pivot 24 with a bifurcated crank 46 formed integral with a yoke 47 which is keyed to a shaft 48 that extends entirely across the machine. On the opposite end there is keyed a bifurcated crank 49 of the same length as 'crank 46 and to it is pivoted a link 34' of the same length as link 34 and fitted with the same adjusting means. On yoke 47 there are two pins 51) and 51 and two projections 52 carrying threaded studs 53 adapted to bear one at a time against a stop 54 mounted in frame member 14.

A thrust block 55 having shoulders adapted to cooperate one at a time with the pins or 51 is pivotally mounted at 56 upon a lever 57 which is pivotally mounted at 58 upon the frame member 14. A follower 59 on the lever bears against the cam 16 to cause reciprocation of the thrust block once for each revolution of the cylinders. The follower 59 is held against the cam by acompression spring 60 surrounding a guide rod 61 which is mounted to swing upon a pin 62 carried by the frame memberM. This spring bears at one end against a tilting block 63 and at the other end against a collar 64 on the rod. Also mounted to turn about the axiss 58 there is a lever 65 which is pivotally connected at one end with thrust block 55 by means of a link 66 and at the other end with a reciprocable throwotf control rod 67. When a throwotf is called for rod 67 moves toward the left until the upper end of thrust block 55 swings toward the right and engages pin 50 on the yoke 47. On the next upward movement of the thrust block the cranks 46 and 49 turn counterclockwise and the outer eccentrics Band 19 turn clockwise.

Inner eccentric 20 carries a bifurcated arm 70 in which is mounted a pivot pin 71 which is received by an eye on one end of a link 72. This link is threaded for approximately half its length beginning at its free end to receive threaded sleeves 73 and'74 which bear against opposed flats on a pin 75 similar to pin 33 and having a smooth bore through which the threaded part of link 72 extends. Pin 75 is mounted in a bifurcated end portion of a bell crank lever 76. Threaded sleeve 74 has mounted thereon a further sleeve 77 having a grooved enlargement 78 like the parts 39 and 40 previously described. An index plate 79 overlying enlargement 73 is provided with a slot 80 which receives a screw 81 threaded into a hole in pin 71. Index plate 79 and enlargement 78 may therefore be adjusted to make the gauge-marks come in the 4 right place to indicate the true relation of cylinders 11 and 12. When an adjustment of the position of cylinder 11 is desired, as when changing from one thickness of paper to another, sleeve '73 is loosened, sleeve 74 is moved to the desired setting and sleeve 73 is again tightened.

A projecting portion 85 of outer eccentric 18 carries a pivot pin 86 upon which the bell crank lever 76 is mounted. The inner arm 87 of this lever extends from pivot pin 86 in a generally radial direction toward the axis of the outer eccentric 18, and the effective length of the arm 87 is substantially the same as the distance between the axis of pivot 86 and the axis 0 of the outer eccentrics. When the blanket cylinder is in the running position the pivotal point of the inner end of arm 87 and the axis of the outer eccentrics meet at O.

In order to hold the eccentric 18against the frame member 14, screws 88 are projected tllrough vashers 89 and through arcuate slots 90 in the extensions 31 and 85 of outer eccentric 18 into the frame. Inner eccentric 20 is retained by a disk 91 which is secured by suitable fastenings to the extremity of shaft 17.

The inner end of arm 87 is pivotally connected with a link 92, the outer end of which is connected by a pivot 93 with a crank 94 that is integral with a yoke 95 which is mounted to oscillate about a trunnion 96 mounted in the frame. This yoke 95 carries two pins 97 and 98 similar to pins 50 and 51. The yoke also carries projections 99' and 100 in which are mounted adjustable threaded studs 101 similar to studs 53, and like those studs engaging one at a time a stop 102 mounted in the frame. A thrust block 103, which may be identical with block 55, is pivotally connected at 104 with one arm of a lever 105 pivoted to the frame at 106, the other arm of the lever carrying a follower 107 which runs upon the cam 16. Follower 167 is held against the cam by a compression spring 108 on a rod 109 pivoted to the frame at 110 and bearing against an arm 111 on the lever. As the lever 105 swings on its pivot, thrust block 163 moves up and'down in the conventional manner of such blocks.

A rod 112 pivotally connected with thrust block 103 serves tomove the block from one position to the other.

This rod extends loosely through a noddle pin 112' in the lower extremity of a lever 113 pivotally mounted on the frame at 114l A compression spring 115 on a rod 116 pivotally connected with the lever 113 below its pivot 114 tends to turn the lever counterclockwise, the spring'bearing at one end against a collar 117 on the rod and at the other end against a perforated block 118 mounted in the frame. A compression spring 119 on rod 112 bears at one end against a collar 120fixed to the rod and at the other end against noddle pin 112'. A second collar 121' on the rod is engaged by the lever 113 when it swings counterclockwise.

At the upper end of lever 113 there is a h0using'122, Fig; 6. A bore 123 extends from one end of this housing inwardly into-a concentric chamber 124. A plunger 125 slidable within chamber 124 is integral with a post 126 which extends through bore 123 and at its outer end is provided'with a knurled head 127. A coil spring 128'surrounding the post within the chamber 124 tends to force the plunger 125 out of the housing into a semicylindrical socket 129 in the side of extension 85 on the outer eccentric 18, as indicated in Fig. 5. A pin 130 mounted in a drilled hole through the post 126 stands normally at the bottom of a pair of slots 131 injthe housing 122 and limits the extent to which the plunger 125 may be projected by the spring. When it is desired to withdraw the plunger to the position illustrated'in Fig; 6 the operator grasps the head 127, pulls itoutand turns it through an angle of 90, whereupon pin 130'may be caused to rest in a shallow groove 132 in the face of the housing at right anglesto slots Operati0n.Therunning-position of the'unit is illustrated in Fig. 1. In this position the blanket cylinder 11 contacts the plate on plate cylinder with suflicient pressure to take the image from the plate onto the blanket, and it contacts a sheet of paper on the impression cylinder 12 with sufficient pressure to print the image on the paper. If for any reason there is an interruption in the feeding of sheets, throwoff control rod 67 is moved to the left by suitable means. Mechanisms for this purpose are well known in the art and since such mechanism forms no part of the present invention it is not herein illustrated. Movement of the rod 67 toward the left swings lever 65 clockwise pulling thrust block 55 toward the right until its upper end contacts pin 50 on yoke 47. This occurs while follower 59 is riding upon the low part of cam 16. When the follower runs up onto the high part of the cam, as indicated in Fig. 2, thrust block 55 is raised from its Fig. 1 position to that of Fig. 2, and the shoulder on the thrust block pushing against pin 50 swings yoke 47 counterclockwise to the position of Fig. 2, the stop 54 when contacted by the stud 53 serving to limit the extent of this motion. This turning of shaft48 counterclockwise exerts a pull on the two links 34 and 34', which turns outer eccentrics 18 and 19 through a small angle about the axis 0 of the outer eccentrics. This causes the axis S of shaft 17 to swing through a small arc about center 0 in a direction downwardly and toward the left. Since the cylinder 11 is mounted upon shaft 17 this results in pulling that cylinder away from cylinder 10 a small fraction of an inch so that contact between the plate and blanket cylinders is broken.

The parts are so arranged, particularly as to the angular position of cam 16, that the throwofi' from the plate cylinder occurs while gaps G and G in the cylinders 10 and 11 are passing each other. In other words, separation occurs after the complete image on the plate is transferred to the blanket. The last sheet is then passing over the impression cylinder and being printed. The throwotf from the plate cylinder does not afiect to any appreciable extent the contact between the blanket and impression cylinders, for the motionof center S of the blanket cylinder is small and is substantially at right angles to the line of centers between cylinders 11 and 12.

When the outer eccentrics 18 and 19 are turned clockwise by the counterclockwise movement of shaft 48 as just described the inner eccentrics move with them, and this is accomplished by my novel operating mechanism for the inner eccentrics. Axis O of the outer eccentrics being concentric with the pivot between the link 92 and the arm 87 of the bell crank, that pivot is not disturbed when the outer eccentrics are moved from the Fig. 1 position to that of Fig. 2. The movement of the outer eccentrics carries pivot 86 around in an are about center 0, and hence there is no movement of arm 87 relative to its pivot 86, and the pin 75 also moves in an are about center 0, transmitting movement through the same angle to the extension 70 of the inner eccentric 20. Eccentrics 20 and 21 being locked together bythe shaft 17, both of them move with the outer eccentrics through the same angle.

When all of the eccentrices are turned clockwise by the oscillation of the shaft 48 and the connections above described, the extension 85 on the eccentric 18 moves clockwise from the Fig. 1 position to the Fig. 2 position, permitting lever 113 to turn counterclockwise under the influence of spring 115. This operates through rod 112 to push thrust block 103 to the right and into contact with pin 98 on yoke 95. This occurs while the follower 107 is running upon the low part of cam 16. When the high part of the cam depresses follower 107 thrust block 103 rises and its shoulder pushes pin 98 upwardly,turning yoke 95 counterclockwise as far as stop 102 will permit, as indicated in Fig. 3. This of course pulls the link 92 downwardly and swings bell crank lever 76 clockwise, which functions through link 72 to turn inner eccentrics 20 and 21 clockwise about their axis I. The center S of shaft 17 therefore moves from the Fig. 2 position to the Fig. 3 position, or in a direction which is substantially away from cylinder 12. This occurs after the imprinting of the sheet passing over the impression cylinder has been completed and while the gap G of the blanket cylinder is passing the gap G of the impression cylinder. Hence no unprinted sheet passes through the unit and there is no offset from the blanket onto the impression cylinder.

When the feeding of sheets is resumed and the control rod 67 is again drawn toward the right from the position of Fig. 3 to that of Fig. 3a, thrust block 55 is swung over toward the left until it contacts pin 51 on yoke 47. The next time the high spot of cam 16 runs under the follower 59 the shoulder on thrust block 55 engages pin 51, turning the yoke 47 clockwise from the position of Fig. 3 to that of Fig. 3a which turns the outer eccentrics 18 and 19 counterclockwise about their axis 0, throwing the blanket cylinder into contact with the plate cylinder. The inner eccentrics again move with the outer ones through the same angle. At the time this occurs, the pivot between the link 92 and the arm 87 of the bell crank is not concentric with the axis 0 of the outer eccentrics, but lies aproximately on a line between axis 0 and stud 93, so that as the extension on the outer eccentric 18 moves counterclockwise in an are around the point 0 there is a slight tendency to impart movement to the bell crank 76 independent of its bodily movement and consequent movement of the inner eccentrics relative to the outer ones, but in practice this movement is so slight as to be negligible. The throw-on between the blanket and plate cylinders occurs as the gaps G and G are passing each other and hence the inking of the blanket begins at the leading edge thereof. When the eccentrics are turned counterclockwise as just stated lever 113 is turned clockwise, thrust block 103 is swung toward the left until it engages pin 97 on yoke and a little later when the high spot of cam 16 bears against'follower 107 crank 94 is swung clockwise from the position of Fig. 3a to that of Fig. 1, thereby turning the inner ec centrics counterclockwise and throwing the blanket cylinder into contact with the impression cylinder. This occurs while the gaps G and G are passing each other and hence before the leading edge of the blanket and a sheet held by grippers 13 come into the line of impression between the cylinders 11 and 12.

In starting a run of printing, it is necessary to ink up the blanket thoroughly before printing is begun, and this should be done while the blanket is out of contact with the impression cylinder. This is readily accomplished with my mechanism by pulling out the head 127 to disconnect the plunger from the socket 129, as in Fig. 6. Now when the control rod 67 is pulled to the right to set in motion the mechanism for turning shaft 48 clock wise and turning the outer eccentrics counterclockwise to throw the blanket cylinder into contact with the plate cylinder the blanket cylinder remains separated from the impression cylinder because the movement of the extension 85 on eccentric 18 is not imparted to lever 113 and that lever remains in its Fig. 3 position. Consequently, thrust block 103 remains out of contact with pin 97 and the inner eccentrics are not operated to swing the blanket cylinder into contact with the impression cylinder. As soon as the inking of the blanket is completed, the operator moves rod 67 to the left to cause thrust block 55 to throw the blanket cylinder away from the plate cylinder. The operator then grasps the head 127 and brings plunger 125 into line with socket 129. He then turns the handle to bring pin 130 into line with slots 131 and the plunger enters the socket due to the action of spring 128. Thereafter the position of thrust block 103 is controlled through lever 113 by extension 85 of outer eccentric 18 so that when feeding of sheets is begun and rod 67 is moved toward the right, both thrust blocks 55 and 103 will be operated in proper sequence to throw'blanket cylinder 11 first toward the plate cylinder and then toward the impression cylinder.

The modification illustrated in Fig. 10 differs from that first described in the respect that the movement of the two sets of eccentrics together takes place as the second part of the throwotf or throwon operation, while the movement of the inner eccentrics alone takes place as the first part of the operation, whereas the reverse is true in the first described form. Some of the reference numerals applied to the different parts of the mechanism are the same as in the first described form. Where the parts in question are of different form but have functions similar to those of theparts to which corresponding reference numbers are applied in the first described form, the numbers are primed. The operation of the Fig. 10 form of the invention may be described as follows.

The parts are shown on the drawing in the ordinary running condition. If a throwofi of impression is to occur the rod 67 is moved to the left which operates through lever 65 and link 66 to shift thrust block 55 to the right against pin 5%. As soon as the high point of cam 16 forces follower 59 outwardly, thrust block 55 is raised which tilts yoke 47' and bifurcated crank 46 counterclockwise about trunnion 43'. This exerts a pull upon a link 92, thereby rocking bell crank 87', 76 clockwise about its pivot 86' which is carried by projecting portion 85 of outer eccentric 18, the latter being stationary at that time. Link 72 is thereby pushed upwardly toward the left imparting clockwise rotary motion to the inner eccentric 20 through the arm 70" thereon. The axis S of shaft 17', which is keyed to and carried by the inner eccentrics, is thereby moved through a small angle from the position illustrated in a direction away from cylinder 1'0, separating the blanket cylinder from the plate cylinder without affecting the relation between the blanket cylinder and the impression cylinder. This will cause the pivot between the bell crank 37, 76 and link 92', which is normally offset slightly from the axis 0 of the outer eccentrics, to move closer to that axis.

The movement of eccentric 29 clockwise causes a cam surface on arm 70' to shift a follower 135 on lever 113 to produce a counterclockwise movement of that lever around its pivot 114' which will be transmitted through rod 112' to shift thrust block 103 to the right against pin 98'. Then in the same cycle as soon as the high spot of cam 16 strikes follower 107, thrust block 103 will be raised to swing yoke 95" and arm 94 counterclockwise, thereby exerting a pull upon link 34 which is attached to outer eccentric 18' and turning that eccen tric clockwise about its axis 0' which will cause axis S of the shaft to move away from impression cylinder 12. Shaft 96', to which yoke 95' is keyed, extendsacross the press and operates similar mechanism to turn the outer eccentric at the other side of the press. tries will move with the outer eccentrics in this latter operation, because the pivot between the bell crank 87', 76 and the link 92' will remain substantially at the center of the outer eccentrics, so that the movement of the pivot 86' caused by movement of the outer eccentric 18' will produce only bodily movement of the bell crank 87, 76 and the parts 72 and 79 connected therewith.

When the throwon occurs the first effect will be the counterclockwise movement of the bell crank 87', 76' to shift the inner eccentrics about their axis l in the counterclockwise direction, whereby the axis S of shaft 17' will move toward the cylinder it). Next the yoke 95' will be turned clockwise back into the position illustrated, forcing link 34', and the corresponding link on the opposite side of the press, upwardly and turning the outer and inner eccentrics together counterclockwise about the axis 0 of the outer eccentrics, which will cause'the axis S'of shaft 17 to move toward cylinder 12 without affecting the relation between cylinders 10 and 11.

In both of the describ'edforms of the invention the The inner eccenmechanismis" suchas to cause throwon and throwoif of the blanket cylinder, first with relation to the plate cylinder, and second with relation to the impression cylinder, and this at the present time I believe to'be the preferred arrangement. However, it will be obvious that by means of changes within the skill of an engineer experienced in the art, throwon andthrowoif can be effected' first with respect to the impression cylinder and second with respect to the plate cylinder, and under some circumstances this arrangement might be useful or desirable. Accordingly, I shall refer hereinafter sometimes to first, second and third cylinders, it being understood that the first and third cylinders may be either plate cylinders or impression cylinders, the second cylinder in each case being the blanket cylinder.

In both of the described forms of the invention there are two oscillatable units, one comprising the inner eccentrics alone and the other comprising both the inner eccentrics and the outer eccentrics moving together, and either one of these two units may be the first to turn in the sequential operation of the mechanism. The movement of the inner and outer eccentrics together as one unit overcomes a difliculty which would be encountered otherwise, namely a wedging action which would be experienced if the outer eccentrics were moved with respect to the inner eccentrics while printing pressure was being exerted between the blanket cylinder and one of the other cylinders.

Having thus' described my invention, I claim:

1. In a printing press, first, second and third cylinders, said second cylinder being adapted to occupy a position in printing relation to each of said first and third cylinders and having a shaft the axis of which is disposed to one side of the plane through the axes of said first and third cylinders, throwoff mechanism consisting of two oscillatable units, the first unit comprising a pair of inner eccentrics in which said shaft is mounted, and the second unit comprising said inner eccentrics and a pair of outer eccentrics in which the in ner eccentrics are mounted, means for turning one of said units to throw said second cylinder out of contact with said first cylinder, means set in motion by the turning of said one unit for arranging the other unit to subsequently throw said second cylinder out of contact with said third cylinder, interconnecting means between said pairs of inner and outer eccentrics effective to tie them together during the turning movement of said second unit, and means effective upon said interconnecting means for moving the same independently to turn said first unit.

2. Throwofl? mechanism as defined in claim 1, where in the said interconnecting means comprises a lever the power end of which is substantially coaxial with the axis of said outer eccentrics while said second unit is turning, the means for operating said first unit functioning to hold said power end stationary during the turning movement of said second unit and functioning during the turning movement of said first unit to swing said lever for operating said inner eccentrics independently of said outer eccentrics.

3. Throwotf mechanism as defined in claim 1, comprising cam operated means functioning during a single cycle of the press to turn. one unit for throwing said second cylinder out of contact with said first cylinder and thereafter to turn the other unit for throwing said second cylinder out of contact with said third cylinder.

4. In an offset printing press, a blanket cylinder. and twoadditional cylinders one of which is a plate cylinder and the other an impression cylinder, said blanket cylinder being adapted to occupy a position in printing relation to both of said two cylinders and having a shaft the axis of which is disposed to one side of the plane through the axesof said two cylinders, a pair of inner eccentrics in which said shaft is mounted, a pair of' outer eccentrics in which said inner eccentrics are mounted, the axis of 9 said outer eccentrics being-located substantially in the plane defined by the axes of said shaft and one of said two cylinders, and the axis of said inner eccentrics being located substantially in the plane defined by the axes of said shaft and the other of said two cylinders, means for turning said outer eccentrics and said inner eccentrics in unison in one part of a cycle to throw said blanket cylinder out of contact with one of said two cylinders while maintaining its relation to the other of said two cylinders, and means for turning said inner eccentrics in said outer eccentrics for throwing said blanket cylinder out of contact with the other of said two cylinders while maintaining its relation to the first of said two cylinders.

5. In a printing press, first, second and third cylinders, said second cylinder being adapted to occupy a position in printing relation to each of the first and third cylinders and having a shaft the axis of which is disposed to one side of the plane through the axes ,of said first and third cylinders, a pair of inner eccentrics in which said shaft is mounted, a pair of outer eccentrics in which said inner eccentrics are mounted, means for turning said outer eccentrics to throw said second cylinder out of contact with said first cylinder, interconnecting means between said pairs of inner and. outer eccentrics for transmitting motion to said inner eccentrics from said outer eccentrics through a substantially equal angle during said movement of said outer eccentrics, and means timed in relation to the movement of the outer eccentrics for operating said interconnecting means for turning said inner eccentrics only to throw said second cylinder out of contact with said third cylinder.

6. Mechanism as defined in claim 5, characterized in that said means for turning said outer eccentrics embodies a rock shaft extending across the machine with cranks at the ends of said rock shaft and links connecting said cranks with the outer eccentrics, and in that said second cylinder is mounted to rotate on its shaft and said inner eccentrics are keyed to the latter shaft, and cam actuated means at one side of the press for turning said rock shaft and said cylinder shaft in sequence during a single revolution of said second cylinder.

7. In a rotary offset printing press, a plate cylinder, an impression cylinder and a blanket cylinder, said blanket cylinder having a shaft the axis of which is disposed to one side of the plane through the axes of the plate and impression cylinders, a pair of inner eccentrics in which said shaft is mounted, a pair of outer eccentrics in which said inner eccentrics are mounted, means for turning said outer eccentrics to throw the blanket cylinder out of contact with the plate cylinder, interconnecting means between said pairs of inner and outer eccentrics for transmitting motion to said inner eccentrics from said outer eccentrics through a substantially equal angle, and means timed in relation to the movement of the outer eccentrics for operating said interconnecting means independently of said outer eccentrics for turning said inner eccentrics only to throw the blanket cylinder out of contact with the impression cylinder.

8. In a rotary ofiset printing press, a frame, a plate cylinder, an impression cylinder and a blanket cylinder, said blanket cylinder having a shaft the axis of which is disposed to one side of the plane through the axes of the plate and impression cylinders, said blanket cylinder being mounted to rotate on its shaft, a pair of inner eccentrics in which said shaft is mounted and by which it may be moved toward or away from said impression cylinder, a pair of outer eccentrics in which said inner eccentrics are mounted to turn, said outer eccentrics being mounted in said frame, means for turning said outer eccentrics to throw the blanket cylinder 01f from said plate cylinder, a pivot carried by one of said outer eccentrics remote from its center of rotation, a lever mounted on said pivot, a link connecting one arm of said lever with one of said inner eccentrics, the other arm of said lever extending from said pivot toward the axis of, said outer eccentrics, and being of a length equal to the distance between said pivot and said axis, and means for pivotally anchoring the last named end of said lever in line with said axis, whereby turning motion of said outer eccentrics is communicated to said inner eccentrics substantially without relative motion between said eccentrics.

9. Mechanism as defined in claim 8 characterized in that said means for pivotally anchoring one end of said lever comprises a reciprocable link, and operating connections for holding said link in said anchoring position or for moving it to swing said lever upon its pivot and there- 1 by turn said inner eccentrics relative to said outer eccentrics to throw said blanket cylinder off from said impression cylinder.

10. Mechanism as defined in claim 9, wherein said reciprocable link is pivoted to the lever substantially at the axis of said outer eccentrics in the operating condition of the press, a crank to which said link is pivotally'connected, said crank being mounted on the frame to turn about a fixed axis, and means for operating said crank to throw off said blanket cylinder from said impression cylinder after said outer eccentrics have been operated to effect throwoif from said plate cylinder.

11. In mechanism of the character described, throwoff means for the blanket cylinder of a rotary ofiset press, comprising inner eccentrics inwhich the cylinder shaft is mounted and outer eccentrics in which the inner eccentrics are mounted, means for turning the outer eccentrics and with them the inner eccentrics to throw off the blanket cylinder from the plate cylinder, a thrust block, means associated with one of said outer eccentrics functioning to swing said thrust block to a given position when said outer eccentrics move to throwoif position, means effective in the last named position of said thrust block for moving it endwise, and operative connections actuated by said endwise movement for turning said inner eccentrics to throw the blanket cylinder off from said impression cylinder.

l2. Mechanism as defined in claim 11, characterized in that said means for turning said outer and inner eccentrics functions also to throw the blanket cylinder onto said plate cylinder and said impression cylinder sequentially in that order, and means for disabling the throwon to said impression cylinder, whereby the blanket may be inked while out of contact with said impression cylinder.

13. In a rotary offset printing press, a plate cylinder, an impression cylinder and a blanket cylinder, said blanket cylinder having a shaft the axis of which is disposed to one side of the plane through the axes of the plate and impression cylinders, a pair of inner eccentrics in which said shaft is mounted and by which it may be moved away from the impression cylinder, a pair of outer eccentrics in which said inner eccentrics are mounted and by which said shaft may be moved away from one of said other cylinders, means for turning said outer eccentrics, interconnecting means between said inner and outer eccentrics adapted to cause said inner eccentrics to turn with said outer eccentrics when the outer eccentrics are turned for throwing said blanket cylinder out of con tact with the said other cylinder, and means sequentially timed in relation to the movement of the outer eccentrics and comprising said interconnecting means for turning said inner eccentrics relative to said outer eccentrics and throwing said blanket cylinder out of contact with the second of said other cylinders.

14. In a rotary offset printing press, a plate cylinder, an impression cylinder and a blanket cylinder, said blanket cylinder having a shaft the axis of which is disposed to one side of the plane through the axes of the plate and impression cylinders, a pair of inner eccentrics in which said shaft is mounted and by which it may be moved away from the impression cylinder, a pair of outer eccentrics in which said inner eccentrics are mounted and by which said shaft may be moved away from the plate cylinder, means for-turningsaid outer eccentrics, interconnecting means betweensaidinner and outer eccentrics movable bodily with said outereccentrics for causing said inner eccentrics to turnwith said outer eccentrics when the outer eccentricsare turned for throwing said blanket cylinder out of'c'ontactwith said plate cylinder, and means sequentially timed in relation to the throwoif movement of the-outer eccentrics for moving said interconnecting means to turn said inner eccentrics relative to said outer eccentrics for throwing said blanket cylinder out of contact with said impression cylinder.

15. In a printing press, first, second and third cylinders, said second cylinder being adapted to occupy a position in printing relation to each of said first and third cylinders and having a shaft the axis of which is disposed-to one side of, the plane through the axes of said first and third cylinders, .throwoff mechanism consisting of two oscillatable units one of which units comprises a pair of inner eccentrics in which said shaft is mounted anda pair of outer eccentrics in which said inner eccentrics are mounted and the other of which units comprises one pair only of said eccentrics, the axis of said outer eccentrics being located substantially in the plane defined by the axes of said shaft and one of said two cylinders, and the axis of said inner eccentrics being located substantially in the plane defined by the axes of said shaft and the other of said two cylinders, means operable to turn one of said units to move said second cylinder relative to one of said first and third cylinders, and means operable subsequently to the turning of said one unit for turning the other unit to move said second cylinder relative to the other of said first and third cylinders.

16. The invention set forth in claim 15 including interconnecting means between said pairs of inner and outer eccentrics effective to tie them together during the movement of that oscillatable unit which comprises the two pairs of eccentrics.

17. In a printing press, first, second and third cylinders, said second cylinder being adapted to occupy a position in printing relation to each of said first and third cylinders and having a shaft the axisof which is disposed to one side of the plane through the axes of said first and third cylinders, throwoif mechanism consisting of two oscillatable units one of which comprises a pair of inner eccentrics in which said shaft is mounted and the other of which comprises said inner eccentrics and a pair of outer eccentrics in which said inner eccentrics are mounted, the axis of said outer eccentrics being located substantially in the plane defined by the axes of said shaft and oneofi said two cylinders, and the axis of said inner eccentrics being located substantially in the plane defined by the axes of said shaft and the other of said two cylinders,imeans operable in response to an interruption in the feeding of sheets to turn one of saidunits to throw said second cylinder out of contact with one of saidifirst and third cylinders, and means operable subsequently to the turning of said one unit for turning the other unit to throw said second cylinder out of contact with the other of said first and third cylinders, each of said turning means being operable also'to turn said units in a reverse direction for moving said second cylinder backinto contact with said first and third cylinders.

18. Themethod ofsequentially throwing-off and throwing-on a blanket cylinder from and to animpression cylinder and from and to a plate cylinder of an offset press wherein said blanket cylinder is disposed to one side of a plane passing through the axes of said two other cyl: inders and wherein said blanket cylinder is provided with a shaft carried in a pair of inner eccentrics and said inner eccentrics are journaled in a pair of outer eccentricspivotally mounted in a frame of said press, comprising turning both pairs of said eccentrics together in one direction about the axis of said outer eccentrics in one step of the throw-off sequence to separate said blanket cylinder from one of said other cylinders, turning one pair alone of said eccentrics in the other step of said throw-off sequence to separate said blanket cylinder from the second of said other cylinders, turning said one pair of eccentrics in a reverse direction in one step of said throw-on sequence to return said blanket cylinder into contact with the cylinder from which it was thrown off by said one pair, and turning both pairs of eccentrics together in a reverse direction in the other step of said throw-on sequence to return said blanket cylinder into contact with the remaining one of said other cylinders.

References Cited in the file of this patent UNITED STATES PATENTS 833,275 White Oct 16, 1906 1,107,843 Robertson Aug. 18, 1914 1,604,278 Goulding Oct. 26, 1926 2,003,798 Barber June 4, 1935 2,121,195 Harrold et al June 21, 1938 2,335,010 Huck Nov. 23, 1951 2,568,761 Peyrebrune Sept. 25, 1951 2,689,524 Wood Sept. 21, 1954 

